The purpose of this research is to understand the processes involved in normal mammalian oocyte maturation. Maturation will be studied by determining the requirements of normal in vitro occyte maturation and examining the changes in metabolism which take place during this period of development. In vitro maturation of mouse oocytes will be examined by (1) determination of the stage(s) of maturation most sensitive to in vitro culture, (2) alteration of the basic culture medium and addition of different cell types (granulosa cells, fibroblasts) to the medium, and (3) determination of methods of selecting, from the ovary, those oocytes most likely to complete in vitro maturation successfully. The metabolism of the oocyte (RNA, protein, energy) during different stages of maturation will be studied using isotope methods already developed in this laboratory for the study of later stages of in vitro development. The information obtained from these studies should provide us with ways of altering the environment to increase the success of in vitro maturation and should aid us in understanding normal oocyte maturation. When the techniques have been developed and the basic information about successful in vitro oocyte maturation has been obtained for the mouse, these studies will be extended to other species.